Prior TIA proves less risky than stroke in AF patients

MONTREAL – Stroke and transient ischemic attack, usually joined at the hip as related histories that each flag a similar need for anticoagulation may in fact not be nearly as equivalent as conventional wisdom says.

^{Mitchel L. Zoler/MDedge News}

Dr. Werner Hacke

Analysis of 2-year follow-up data from the GARFIELD-AF registry of more than 52,000 patients with newly diagnosed atrial fibrillation (AF) showed that, while patients with a history of stroke had significantly elevated rates of both all-cause mortality and stroke, those with just a history of a transient ischemic attack (TIA) had mortality and stroke rates virtually identical to AF patients with no history of a cerebrovascular event.

“A history of TIA only is not a reliable predictor of an increased risk for events,” Werner Hacke, MD, said at the World Stroke Congress. “A history of TIA should be removed from scores estimating the risk for stroke and systemic embolism in AF patients,” said Dr. Hacke, professor and chairman of the department of neurology at the University of Heidelberg (Germany).

“The weak predictive power of a history of TIA is probably caused by the relatively low reliability of establishing the diagnosis of TIA,” especially when the diagnosis is made by someone who’s not a neurologist. “It’s a very fuzzy diagnosis,” even for a neurologist, and it consistently confounds other clinicians, he said in an interview. “I’d be really careful of deciding to anticoagulate a patient [with AF] based on a history of TIA.” In the GARFIELD-AF registry, “I’m convinced that most people with a history of TIA actually never had a TIA.”

Dr. Hacke has been unable to find a good explanation of why, years ago, TIAs began to get routinely lumped with stroke. “I asked all the old AF guys when did TIA start coming in and why, and none of them could remember,” he said. “At first, they talked about a history of ‘cerebrovascular events,’ but then that became stroke and TIA, and it was as if it was one word,” always said in the same breath. Both the CHADS₂ score (JAMA. 2001 Jun 13;285[22]:2864-70) and the CHA₂DS₂-VASc score (Chest. 2010 Feb;137[2]:263-72) make a history of stroke or TIA, as well as thromboembolism, coequal risk factors that count for 2 points when calculating the thrombotic risk score for a patient with AF.

To test whether this really made sense, Dr. Hacke and his associates decided to look at the separate consequences of a history of stroke only, compared with a history of a TIA only. They used data collected in GARFIELD-AF (Global Anticoagulant Registry in the Field), a multinational registry with 51,670 patients newly diagnosed with AF, followed for 2 years, and with complete information on their stroke and TIA history. This included 5,617 patients with a history of at least one diagnosed cerebrovascular event, including 3,362 diagnosed with stroke only, 1,788 diagnosed with TIA only, and the remaining patients diagnosed with both types of events.

When compared with AF patients without a history of any type of cerebrovascular event, those with a history of a stroke only had a statistically significant 29% increased rate of all-cause death and a 2.3-fold higher rate of stroke after adjustment for baseline demographic and clinical differences. In contrast, the patients with a history of TIA only had mortality and stroke rates during follow-up that did not differ significantly from the comparator group.

mzoler@mdedge.com

Source: Hacke W et al. World Stroke Congress, Abstract.